Facebook revealed in its third quarter earnings report today that mobile ad revenue represented 49 percent of its $1.8 billion in overall advertising revenue. The news should reassure investors that had been worried about the monetization gap between mobile and desktop for companies like Facebook.

The company posted strong growth in mobile users over the quarter with 45 percent growth year over year to 874 million monthly active users (MAUs). With 1.19 billion MAUs overall, Facebook now has 73 percent of its user base on mobile.

So far, Facebook stock is up almost 16 percent in after-hours trading.